Organic Light-Emitting Diodes (OLEDs) are known as an emerging technology in the applications of next generation of flat panel displays due to their excellent characteristics of self luminescence, no need of any backlight source, high contrast ratio, small thickness, wide angle of view, high response speed, availability for flexible panels, wide service temperature range, simple structure and manufacturing process and the like.
FIG. 1 is a sectional view of an array substrate in an existing OLED display device. As shown in FIG. 1, the array substrate includes a glass base substrate 1 (with refractive index n of about 1.5) and an electroluminescent device 2 disposed above the glass base substrate 1, wherein the electroluminescent device 2 includes an anode 3, an electroluminescent layer 4 and a cathode 5 which are successively stacked from bottom to top. Both the anode 3 and the cathode 5 are made of transparent and conductive oxide (with refractive index n of about 2.0), and the electroluminescent layer 4 is made of organic electroluminescent material (with refractive index of about 1.7). The electroluminescent layer 4 emits light of a certain color under the action of the anode 3 and the cathode 5, and light generated by the electroluminescent layer 4 successively transmits through the anode 3 and the glass base substrate 1 to enter human eyes.
However, in the process of light transmitting from the electroluminescent layer 4 to the human eyes, as the refractive index of the anode 3 is greater than that of the glass base substrate 1 and the refractive index of the glass base substrate 1 is greater than that of the air, a part of light will be totally reflected on a boundary between the anode 3 and the glass base substrate 1 and a boundary between the glass base substrate 1 and the air, so that light refracted from the glass base substrate 1 is reduced, and the light extraction efficiency of a display device equipped with such array substrate is low.